Feeding and rotating means for electrodes



July 3, 1923. ma-793 A. P. DAVIS FEEDING AND ROTATING MEANS FOR ELECTRODES Filed March 27, 1917 2 Sheets-Sheet l m v H N Y 47 J r I In I {L J 4 I INVENTOR ARTHUR P. DAV/5 July 3, 1923.

1,460,793 A. P. DAVIS FEEDING AND ROTATING MEANS FOR ELECTRODES Filed March 27, 1917 2 Sheets-Sheet 2 I INVENTOR ARTHUR F3 DAV/5 Patented July 3, 1923.

- UNITED. STATE PATENT OFFICE.

ARTHUR P. DAVIS, OF BROOKLYN, NEW YORK, ASSIGNOR TO ELMER A. SPEBRY,

- 013 BROOKLYN, NEW YORK.

FEEDING AND ROTATTNG MEANS FOR ELECTRODES.

Application filed March 27, 1917. Serial no. 157,608.

length, but to maintain the positive crater at the focus of the projector. The invention relates especially to an are light in which the positive electrode holder is normally stationary, and the electrode fed through and preferably also rotated within the go holder, to maintain the crater symmetrical and in focus. The main object of the invention is to improve upon existing types of mechanism for both rotating and feeding the electrode.

5 Referring to the drawings in which what ll now consider to be the preferred form of my invention is shown:

Fig.1 is a side elevation partly in section of the electrode holders, a portion of so the Searchlight drum being shown in connection therewith. I Fig. 2 is a section through the positive electrode holder takien approximately on broken section of line.2--2-of Fig. 4:.

Fig. 3 is a detail of the linkage connecting the thermostat and hand feeding means to the feeding mechanism proper.

Fig. 4 is a section approximately on line 4-4: Fig. 6.

4 Fig.5 is a plan view of the positive electrode holder.

Fig. 6 is a front elevation thereof.

Fig. 7 is an elevation, partly in section of a modified positive holder.

My invention is shown in the drawings as applied to a Searchlight, a portion of the Searchlight "drum being indicated at 1 with the slidable removable control box 2 carrying the lampstructure proper mounted in runways 3. I y c Both electrode holders 4 and 5 are shown as mounted on top of the box "onsupporting legs 81 and 82 respectively. The negative electrode holder 4 is shown as a split tubular member 6 through which the electrode 80 is fed by feed rollers 7 said rollers are actuated through shaft 8 by a suitable form of feeding mechanism designed to maintain the arc length and preferably contained within the box 2.

The positive holder 5 is shown as comprising a hollow body 9 at the forward end of which are metallic cooling ribs 10. Preferably also the forward end is provided with a light shield 11 adapted to cut off direct rays from the arc, especially from the negative electrode and also aiding in cooling the forward portion of the holder. Adjacent the arc the holder is preferably pro-- vided with a refractory sleeve 12 made of quartz or the like.

Current is preferably introduced to the electrode 100 through the entire holder, the holder being made of copper or other good conducting material for this purpose and also to aid in the rapid dissipation of heat. lln order to insure good contact with the electrode, spring pressed brushes 53 and 54 are shown as extending through holes in the forward portion of the electrode holder and are pressed into place by pivoted strips 55 which are pressed downwardly against the brushes by compression springs 56 acting against the rearward portions thereof.

The mechanism proper is shown as mounted within the space 9 and comprises preferably one or more rollers 13 and 13' adapted to engage the electrode. These rollers, however, are positioned very differently from the ordinary feed rollers, such as feed rollers 7, for instance. Rollers 13 and 13' have their plane of rotation at a substantial angle to the longitudinal axis of the electrode. In Fig. 1 the rollers are shown at right angles to said axis in which position the electrode would be rotated thereby, but not fed. The rollers are mounted so as to turn about an axis to vary their plane of rotation and thereby'varying the rate of feed; i. e., to change the feed from zero to whatever rate or rates is necessa or de-. sirable. For this purpose the rol er 13 is shown as journaled in frame 14, having a swiveled mounting 15 in the casing 9. Both rollers 13 and 13 are preferably continuously driven as from a shaft 16 through bevel gears 17. A chain or belt 18 extending between pulleys 19 and 20 on the axles of rollers 13 and 13 respectively maybe used to rotate roller 13 from roller 13'.

The rollers are preferably yieldingly pressed towards the electrode by springs 120 located between the adjacent cap 21 and a shoulder on frame 14. Handles 22 may be provided to spread the rollers to insert the carbon. By turning the handles outwardly (see Fig. 2) about their pivots 22 the rollers are drawn against springs 120 by reason of the engagement of the inner ends 122 of the handles acting as cams against the tops of caps 21. Preferably I provide automatic means to adjust the plane of rotation of'the rollers which is operated in effect by the position of the tip of the electrode.

It will readily be seen that the rate of feeding is a function of the angle which the axis of rotation of the roller makes with the longitudinal axis of the electrode so that by varying the said angle the feed may be adjusted from zero to maximum at will. In operation, the angle through which the rollers are turned as shown in Fig. l is preferably small (see Fig. 4) so tha'tthe. rate of rotatlon of the electrode is not appreciably less when feeding than when rotating only.

The feeding of the electrode when the rollers are turned to the feeding position, it will be noted, is effected through the following instrumentalities, first the angular position of the axis of rotation of one or both rollers in a plane which is preferably substantially parallel to the axis of the electrode and second the rotation of the electrode and roller.

As above stated, in searchlights it is desired to maintain the crater of the positive electrode in a predetermined relation to the projector. For this purpose I provide some form of device located adjacent the are, preferably slightly to the rear of the arcing face of the positive electrode, and responsive to the proximity of the arc flame. As shown, I locate adjacent the electrode and preferably behind the tip thereof a thermostat consisting of one or more strips of metal 2323' suitably mounted on the face of the electrode holder; Any suitable material having a high coetlicient of expansion and melting; point may be employed for strips 23, such as brass. Strip 23is shown as secured at its base to the holder and provided at its tip with a knife edge 24 engaging cross beam 25. The other strip 23' is also provided with a similar knife edge 24 engaging the opposite end of said cross beam. Adjacent its lower end" said strip is pivotally secured to a bell crank lever 27 shown as pivoted at 28. Said lever extends rearwardly through an aperture 29 in the holder and is shown as bent at an angle at 30 to extend across space 9. Adjacent its far end said lever may be resiliently secured to the holder 5 as by means of spring 31, ex-

. tending between said end and adjustable screw 32. Lever 27 is'pivotally secured at 74 to a link 33 which in turn is connected by link 34 with T shaped lever 35. Pivoted to each arm 36 of said lever is a link 37 which is pivoted adjacent its other end to a portion 38 of the journal frames. 14 and 14.

For operating the feeding mechanism by hand from without the searchlight drum a link 40 may be pivoted to an intermediate portion 75 of link 33. A lever 70, pivoted to the holder at 71 is shown connecting the rod 41 extending without the drum. Said rod is shown as supported at its base by a rocker arm 42 to which is secured adjacent its outer end a wire 43. Said wire extends without the casing through a flexible tube 44 and is connected to a small drum 45 located within a control box 46. The operator turns knob 47 on the shaft of drum 45 which pulls the wire 43 to raise rod 41. This action, it will be seen, will readily turn the rollers'in opposite directions so as to feed the electrode in one direction or the other. The wire is normally maintained taut by spring 50. 'For operating the rollers a mo- .tor. 51 is shown located within the control box 2, said motor being connected to shaft 16 through a system of reduction gears 90.

The operation of the form of my invention disclosed is as follows:

The thermostat is so located and designed as to maintain the positive crater at a predetermined distanoe in front of it. It will readily be seen that this will also maintain the positive crater in the desiredposition with respect to the projector since the electrode holder is normally fixed. If the positive crater should burn back 'toward the holder the increased heat due to its closer proximityto the thermostat would cause the strips 23, 23' to expand, thus allowing the spring v31 to pull the inner end of the bell crank lever 27 upwardly. This, it will be seen, will rotate 33 about point 75 and r0- tate lever 35 in the direction shown in Fig. 4. The rollers will thereby be turned so that a component of the rotation will be in the direction of the axis of the electrode and the electrode'will be fed forwardly thereby. As the electrode approaches its normal position the feed will be slaokened.

If the electrode" should advance too far from the thermostat, it would cool sufficiently to cause rotation of the lever 35 in the opposite direction from that shown in. Fig. 4, thereby feeding the electrode backwardly. It should be noted that by this feeding mechanism not only is the electrode fe'd when it is in the. desired position which is not the case in existing mechanism of this character, but its rate of feeding is proportional to the distance itiisaway from said position. In other words, according to my invention, the electrode in operation feeds very slowly at the desired rate continuously.

shown in Fig. 1. But it back slightly the air will expand sufficiently will be moved thereby, and lever 35 through the connections described above, the point 74 being the fixed point in the system when feeding by hand. The strength of springs 31 and 50 is preferably very much greater than the force required to turn the rollers, so that point 75 is virtually a fixed point when the automatic feed is operating. It is of course obvious that the hand feed may be used in conjunction with the automatic feed to adjust or alter the same, since the two are difi'erentially connected. In this connection it should be observed that by means of the hand feed the permanent posit-ion of the crater may be readily adjusted; that is, the hand feed may be used to position the electrode out of focus with the projector if desired, at which point the thermostat will maintain the electrode with the same precision that it will maintain the electrode in focus, since the adjustment of the hand feed will alter the relation between the thermostat and the feed rollers.

In Fig. 7 I have illustrated a modified form of thermostat for governing the position of the feed rollers. According to this form the metallic thermostat is replaced by a fluid actuated device. As shown this device consists of an air tight container 123 secured to the forward portion of the holder 11 adjacent and preferably above the arc, so that the arc flame sweeping upwardly from the arc will pass in close proximity thereto. Said container is connected by tube 101 to an expansion chamberor chambers 102. Said chambers at the top abut against a fixed stop 103 which is shown as adjustably secured on threaded rod 104,-, and have secured to their under surface a rod 29' which extends within the holder and corres onds to the vertical portion of the rod 2 in the first described modification. The chambers 102 may be constructed of thin corrugated sheet metal so that the under'surface will be pushed downwardly or drawn upwardly by variations in the pressure of the air or other fluid therein contained. The! pressure of the air is so ad- 'usted with respect to position of the rollers that with the electrode crater in proper position the rollers will be positioned as the crater burns to turn the rollers to feed the electrode forward as will be readily apparent, and on its the-other hand if the crater becomes advanced too far the air will cool sufficiently to feed the electrode backwardly.

Iprefer to so adjust the air pressure in to such use.

chamber 123 that said pressure will be about equal to atmospheric pressure when the electrode is in'the correct position.

lln accordance with the provisions of the patent statutes, l have'herein described the principle of operation of my invention, together with the apparatus, which I now con sider to represent the best embodiment thereoi", but T desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends Having described my invention, what I claim and desire to secure by Letters Patent 1. The combination with an electrode holder, of mechanism for feedin the electrode therethrough including a p ura-lity of feed rollers, means for mounting the same to engage at substantially opposite points the electrode, means for oppositely altering the planes of rotation of each roller to vary the rate of feeding during the operation of the lamp and means for driving the rollers.

2. The I combination with an electrode holder, of mechanism for feedin the electrode therethrough including a ood roller adapted to engage the electrode, a swivel mounting for said roller in said holder, means whereby said roller may be turned in said mounting to alter the rate of feed and means for rotating said roller.

3. The combination with an electrode holder, of mechanism for rotating the electrode therewithin, includin a plurality of rollers having their norma planes of r0- tation at acute angles to the axis of the electrode and adapted to engage the same at spaced points, a swivel mounting for each of said rollers, mechanism for turning the rollers in their respective mountings to vary iaid angles, and means forrotating the role rs,

4;. A feeding and rotating mechanism for electrodes comprising an electrode engaging ing said surface while in engagement with the electrode to simultaneously feed and rotate the same and means for lifting said surface out of engagement with said electrode. 5. In a searchlight, the combination with a projector and a normally fixed electrode holder, of means for maintaining'the fare in respect to the a predetermined position with projector comprising a control member mounted on said holder, mechanism also on said holder for feeding the electrode there through, an adjustable device also on sai holder and differential mechanism connecting said member, device, and mechanism for an electrode holder, of means for maintaining the arc in predetermined positions including a thermostat positioned at a: predetermined distance back of the normal position of electrode tip, power driven mechanism fonfeeding the electrode, mean connecting said thermostat and said mechanism for controlling the rate of feed and adjustable means connected to said means adapted to alter the relation between the thermostat and said mechanism.

7. In an are light, the combinaiton with an electrode holder, of means for maintaining the are in a predetermined position ineluding a bar secured t a point to the forward portion of the holder, means mounted on the holder for feeding the electrode therethrough, and mechanism connectin a spaced point on the bar to said means and adapted to alter the rate of feed.

8. In a flaming are light in which the negative flame sweeps past the positive crater in a substantially uni-directional plume, the combination with an electrode holder, of a feeding means for the electrode, and adevicepositioned to the rear, but in the path of said plume as the electrode is consumed, said device acting to cause actuation of said means when said plume ap proaches within a predetermined distance.

In testimony whereof I have aifixed my signature.

ARTHUR P. DAVIS. 

